The nature and function of helper and suppressor factors will be investigated further. Several aspects will be extended this year, such as the analysis of factors derived from human volunteers. These will be produced by methods described, and analyzed serologically. The control of the response to insulin in normal individuals will be investigated. Attempts will be made to obtain factors to beef and pork insulin, and their specificity will be ascertained. Serological analysis of these factors will continue, using rabbit and mouse antisera, raising antisera to human factors, and attempting to raise monoclonal antibodies to factors.